Make request module compatible with python3

[ghost]

The tricky parts is urllib differences, the easiest solution is to
always use 'future' package. Note: this can be dropped once
compatibility with python2 is no longer required.

Notice: I have not done extensive testing with python2.

[guyzmo]

don't forget to (at least) add from __future__ import print_function. I'd add as well unicode_literals.

[guyzmo]

I'm ok to switch to requests, when I wrote this code I did not know about it (and chances are it did not exist, or it was too immature to be used).

As I'm not much an user of this project anymore, I'm always happy to drop py2 support on it. But then, we need to make sure that all possible projects depending on this library don't get upgraded by pip to a non-py2 compatible version.